Rubbing apparatus



Aug. 4, 1970 s. L AMPERT RUBBING APPARATUS Filed Dec. 18, 1968 INVENTOR G. LAMPERT xbn (Mr-110M aqent United "States Patent 3,522,681 RUBBING APPARATUS Gerald Lampert, 21 Prince Charles Drive, Toronto 19, Ontario, Canada Filed Dec. 18, 1968, Ser. No. 784,608 Int. Cl. B2411 17/00 US. Cl. 51358 4 Claims ABSTRACT OF THE DISCLOSURE A sheet of sandpaper supported on a platen; the sandpaper being releasably attached to the platen by recessed grippers formed of a piled fabric of the type known commercially as Velcro (trademark).

The invention relates to rubbing apparatus which is operable to rub an abrasive or like rubbing element against a workpiece to smooth or polish it, for example.

A familiar type of rubbing apparatus as visualized by the invention is the conventional rotary sander which includes a circular turntable or platen and driving means for rotating the platen about its axis. The platen is wholly or, at least, substantially formed of a substance, such as an elastomer, which is resilient and flexible to conform to the contours of the workpiece while it is in operation and has a normally fiat surface on which a discoid rubbing element--e.g. sandpaper or emery clothis concentrically and corotatably disposable; the said rubbing element being flexible to remain flat on the platen as it couforms to the contours aforesaid.

Said rubbing element-hereinafter referred to as a sanding disc for the sake of convenience-is expendable and should therefore be replaceable on the platen from time to time. To this end, facilities of various sorts are provided by the prior art for securing the disc in operative disposition on the platen so that it is conveniently capable of removal and replacement as and when necessary.

A broad object of the invention is therefore to provide such facilities detachably attaching a sanding disc to a platen which constitute an improvement over the prior art and are simple, reliable in use, economical, unobtrusive, easy to manipulate, and which will not interfere with or complicate the operation of the rubbing apparatus.

A further object related to the foregoing is to provide facilities as aforesaid which will adapt themselves readily to the flexing of the platen and the sanding disc in normal use without thereby weakening the interattachment of these elements or imperilling the sanding disc.

More specifically, the invention seeks to provide such facilities in the form of complementary grippers; each said gripper being formed of two complementary parts mounted, respectively, on the platen and on the sanding disc.

As a further object, the invention seeks to provide structure including a platen and a sanding disc equipped with grippers for detachably interattaching the sanding disc and the platen with the gippers sandwiched therebetween; said interattachment being effected without disturbing the essential flatness of the disc on the platen and said grippers being still further adapted to yield in response to the flexing of the platen and sanding disc as well without substantially disturbing the interattachment aforesaid or the flatness of the disc on the platen.

A still further object of the invention is to provide structure including grippers as and for the purpose aforesaid; the specific mounting of the grippers reinforcing their restraint of radial slippage of the disc on the platen.

A still further object of the invention is to provide said grippers as and for the stated purpose arranged to assist 3,522,681 Patented Aug. 4, 1970 in the centering of the disc on the platen and for the resistance of the disc to detachment from the platen under centrifugal stresses.

A colateral and important object of the invention is to provide a simple and inexpensive sanding disc equipped with grippers as aforesaid for attachment to a platen of the type described.

The invention generally achieves the foregoing and other more or less broad objects of the invention hereinafter in part stated and in part obvious by the use of grippers formed of complementary piled fabrics whose piles are capable of interlocking with each other under relatively slight pressure; the piled fabrics being of the type generally disclosed in De Mestral-U.S. 2,717,437 and commercially known under the trademark-Velcro.

Complementary patches of these fabrics are attached to a platen and to a sanding disc as herein contemplated for releasably securing the sanding disc to the platen all as set forth in greater detail in the following description of the elements, parts and principles constituting the invention; a preferred embodiment thereof being illustrated by way of example only in the hereunto annexed drawings wherein like reference devices refer to like parts of the invention and wherein:

FIG. 1 is a broken isometric view of a rotary sander as contemplated by the invention, particularly showing the platen, the motor or driver, and the sanding disc mounted on the platen;

FIG. 2 is an isometric, substantially plan view of the platen of FIG. 1 with one edge of the sanding disc raised to show the disposition of grippers therebelow;

FIG. 3 is a sectional view of a fragment of an instant platen with a sanding disc mounted thereon, and

FIG. 4 is a view corresponding to FIG. 3 particularly showing the nature of the complementary grippers contemplated by the invention.

As will be understood and is, in any event, shown in the drawings, the rubbing element of the invention, herein typified by the illustrated sanding disc 2, is fastened by paired complementary patches 44 of the piled fabric aforesaid to lie flatly and concentrically on platen 8 in the manner previously described with the said paired and complementary patches 44 sandwiched therebetween and releasably meshed and interlocked with each other.

One of each of said pair of patches is secured to the bottom of the sanding disc 2its abrasive or work surface 9 being herein referred to as its top-While the other patch 4 is disposed on the platen 8 so that the said complementary patches 44 on the disc 2 and platen 8 will register with each other when the sanding disc 2 is superposed flatly and concentrically on the platen 8.

While it is not inconceivable that, under appropriate conditions, the sanding disc 2 and platen 8 may be adequately interattached by a single pair of patches 44, it is obviously preferable that two pairs or more Within reason be utilized for the purpose.

Ideally, three or four such pairs, uniformly spaced both radially and circumferentially of an average sanding disc 2 and platen 8, will not only enhance the interattachment thereof but will also assist materially in expediting centering of the disc 2 on the platen 8.

As explained in said US. Pat. No. 2,717,437, the piled fabrics which constitute the patches 4-4 aforesaid are respectively provided with raised and relatively stilf pile loops 10 illustrated herein in FIG. 4; said loops being cut open as shown so that their bights form upright hooks 12 which mesh and interlock with the hooks 12 of complementary patches 4 when the two are pressed together. As shown in the patent aforesaid, the hooks 12 on each patch 4 are rotated or otherwise displaced degrees relative to 3 the hooks 12 on the complementary patch 4 which, of course, may be achieved by a simple and appropriate rotation of the patches 44 themselves relative to each other.

When enmeshed with each other, the complementary patches 44 form a relatively thick body threatening to elevate the sanding disc 2 off platen 8 when sandwiched therebetween. The invention meets this contingency by providing sockets 14 at appropriately oriented and spaced locations on platen 8 and one patch 4 of each said pair is disposed in a said socket 14 whereby its meshing with its complementary patch 4 on sanding disc 8 takes place within the socket 14 and elevation of the sanding disc 2 or the formation of a promontory thereunder is thereby avoided.

In sanding apparatus of the contemplated type, the sanding disc 2 is often spun at relatively high speeds which may tend to develop correspondingly high centrifugal stresses.

To enable it to follow the contours of a workpiece, the platen 8 is preferably formed of an elastomer rendering it resilent flexible particularly in its border areas 16 adjacent its rim 18; the sanding disc 2 being, of course, limp hence flexible enough to follow the flexures of the platen 8. Having regard thereto, a significant advantage inherent in the use of fabric grippers as hereinbefore described resides in the fact that the said grippers, the fabric patches 44, will also yield and adapt themselves to the flexures of the platen 8 without relinquishing their hold on each other.

Preferably, the sockets 14 are dimensioned to provide reasonably snug accommodation for the patches 4 on the sanding disc thereby providing an additional restraint against slippage of sanding disc 2 on platen 8 in use as will be understood and a further advantage afforded by the present sockets 14 is that they simplify and expedite centering of the sanding disc 2 on platen 8.

By way of summary, the foregoing submission discloses rubbing apparatus which includes a circular platen 8 and means for rotating it about its axis; the platen 8 being formed of resilient and flexible materials, which may be elastomeric, to permit its borders 16 at least to flex in use.

In addition, the invention further visualizes a sanding disc 2 which is concentrically superposable on the platen 8 for co-rotation therewith; grippers being provided for interattaching the sanding disc 2 and platen 8 in the aforesaid superposed position of the co-rotating parts; said grippers being recessed into the platen 8 to maintain flatness of the sanding disc 2 thereon.

Each said gripper is constituted by paired patches 44 formed of fabric as disclosed in U.S. 2,717,437 which mesh with and interengage each other when pressed together.

One patch 4 of each pair is secured to the platen 8 and the other to sanding disc 2; they being respectively so located that they may be brought into registration with each other when the sanding disc 2 is concentrically superposed on platen 8 and may be disengageably interlocked with each other by the application of pressure; disengagement being effected by pulling the sanding disc 2 oh the platen 8.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departure from the inventive idea as defined by the following claims.

What I claim is:

1. Rubbing apparatus comprising, in combination:

a flat resilient platen movable at relatively high speeds;

a relatively thin rubbing element with an uninterrupted rubbing surface contiguously and flatly disposed on said platen;

complementary grippers carried peripherally on said platen and on the bottom of said rubbing element respectively effecting detachable interengagement of said platen and rubbing element with said grippers being recessed in said platen to a depth maintaining the flatness of said rubbing element on said platen; said platen and rubbing element being respectively coflexible in use, said complementary grippers being also flexible and capable of limited yield without detachment permitting said platen and rubbing element to move relative to each other when co-flexing as aforesaid.

. Rubbing apparatus as claimed in claim 1 wherein: plurality of sockets are spaced peripherally around said platen accommodating the interengagement of said complementary grippers therein at a depth maintaining the flatness of said rubbing element on said platen, said sockets being contoured to closely embrace the grippers therein.

3. Rubbing apparatus as claimed in claim 2 wherein:

said sockets are regularly spaced in said platen, there being a corresponding spacing of the sites at which said complementary grippers interengage with each other.

4. Rubbing apparatus as claimed in any one of claims 1, 2, or 3 wherein:

said complementary grippers are respectively constituted by fabrics having piles which interlock releasably with each other.

References Cited UNITED STATES PATENTS 421,763 2/1890 Rogers 51382 2,991,596 7/1961 Walters 51-376 3,302,232 2/1967 Wasiloif 15--230.17 3,346,904 10/1967 Armstrong 15-230.12 3,391,434 7/1968 Girard 24-204 OTHELL M. SIMPSON, Primary Examiner 

